Factors influencing the Martensitic interactions in Ni50Mn35Sn15: An EXAFS study

TL;DR

This study uses EXAFS to investigate local structural distortions and hybridization changes in Ni50Mn35Sn15 during its martensitic transition, revealing insights beyond traditional diffraction methods.

Contribution

It provides detailed local structural analysis of Ni50Mn35Sn15's phase transition using EXAFS, highlighting distortions not visible in diffraction studies.

Findings

Significant local structural distortions in the martensitic phase.

Evidence of local distortions in the cubic phase from EXAFS.

Changes in hybridization affecting electronic structure during transition.

Abstract

Extended x-ray absorption fine-structure (EXAFS) measurements have been carried out on Ni$_{50}$Mn$_{35}$Sn$_{15}$ in the austenitic and martensitic phase. The temperatures associated with structural and magnetic phase transformations are obtained from magnetization measurements. The system orders ferromagnetically below 319 K while the structural phase transition occurs at T$_M$ $\sim$ 200 K. EXAFS measurements have been carried out at Mn and Ni K-edges and changes associated with respect to the local structure of these absorbing atoms are compared. Significant changes in the nearest neighbour interactions are seen as the system transits to the low temperature martensitic phase. EXAFS provides evidence for local structural distortion even in the cubic phase that is not seen from the x-ray diffraction studies. The results obtained are understood in terms of changing hybridization between the constituent atoms that influence the electronic structure at the Fermi level, associated with the austenitic-to-martensitic transition.